Demountable coaxial gas-cooled current leads for MRI superconducting magnets

To fabricate a demountable current lead for MRI (magnetic resonance imaging) superconducting magnets with less heat loss, the heat transfer equation of a gas-cooled current lead is introduced. The authors discuss the character of demountable coaxial gas-cooled current leads and make careful selection of lead materials. Leads of 250 A for MRI magnets were made and tested. It is concluded that these current leads are adaptable to all kinds of closed-loop superconducting magnets and very convenient to use. The lead is safe to use even when there is no helium gas glow in it.<>